I mean, it does also illustrate how the empire's strength lies in numbers and resources, and not in superior skill. There's some evidence that stormtrooper accuracy is a lot better than popular media gives credit for (e.g. "these blast points are far too accurate for sand-people,") and the only reason stormtroopers miss as much as they do in the movies is because they are under Vader's orders not to injure Luke and Leia, which may or may not be true, but the battle on endor shows how susceptible the armor is to guerilla warfare that does, in fact, utilize those lower-tech weapons. I'm sure if the empire cared enough about the efficacy of the armor, they could develop a suit that incorporated shield technology and win battles with a fraction of the troops they use, but again, the suit's primary function is to mark these shock troops as the face of an insurmountably vast empire. I would not be surprised if the poor defensive qualities of the armor are intentional, to foster a strategic message to the empire's enemies that says "we don't care how many you kill, there will always be more."

The blasters used in the movie era are... Basically unstoppable? They're the pinnacle of weapon tech as far as mass arming is concerned.

AFAIK no source goes into this, but I've always interpreted the Star Wars universe as having basically invented every single thing that it's possible to invent in their universe. Technology gets better or worse generation to generation based on how unified society is and the proximity of the manufacturer to certain hyper-rare resources, ie the Empire was able to build the Death Star not because they invented a really big laser, but because they centralized enough military manufacturing in one place to actually be able to build it.

Anyway that's the only way I can think of to square the universe's technology being basically indistinguishable between the three trilogies and stuff like KOTOR.

A mook? What's a mook? You can't call me a mook.